How to search text files for patterns efficiently

If grep is one of your favorite tools, chances are that you will like ack even better. ask a Perl-based command-line utility similar to grep, but designed to improve the search speed and capabilities of grep. Especially if you are a programmer, I strongly recommend replacing grep with ack. The usage of ack is heavily optimized for code search, so a programmer can perform complex search on source code trees with fewer keystrokes.